Hybrid Static and Time-Modulated High-Selectivity Nonreciprocal Filter Using Substrate-Integrated Waveguide and Stripline Resonators

This manuscript reports a design of nonreciprocal bandpass filter (NR-BPF) using substrate-integrated waveguide (SIW) and time-modulated stripline resonators (SLRs). The filter comprises two SIW cavities and two SLRs, where the latter are integrated with time-modulated capacitors to introduce nonreciprocal response. By directly inserting SLRs within SIW cavities, this architecture increases the filtering order without additional volume, achieving the circuit miniaturization. Simultaneously, the coupling between time-modulated SLRs and static SIW cavities enables the filter to achieve low insertion loss and ultra-high selectivity. To validate the proposed concept, a NR-BPF operating at 2 GHz was designed and simulated.